Sex-specific Pediatric Reference Research Articles

Highly sensitive tandem mass spectrometric measurement of serum estradiol without derivatization and pediatric reference intervals in children and adolescents.

Monitoring estradiol (E2) is important for determining the onset of pubertal development as well as in the evaluation of girls with precocious puberty. However, E2 measurement remains an analytical challenge in children, who have lower circulating levels. We developed and evaluated a simple and sensitive LC-MS/MS procedure for serum E2 quantification in pediatric populations and established age- and sex-specific pediatric reference intervals. Residual patient serum samples were used to evaluate the analytical performance of our in-house LC-MS/MS E2 assay. The evaluation included accuracy, precision, linearity, functional sensitivity (LLoQ), and method comparison. Age- and sex-specific pediatric E2 reference intervals were also established from a cohort of 405 healthy children (birth to 18 years) recruited with informed consent. Age- and sex-specific differences were assessed, and outliers were removed. Reference intervals were established using the robust method. The assay imprecision was<5.3 %. Assay linearity ranged from 13.7 to 1923.3 pmol/L. The LLoQ corresponding to a CV of 20 % was determined to be 8.9 pmol/L. Bland-Altman analysis revealed a mean bias of 29.3 pmol/L or 9.1 % between our LC-MS/MS E2 assay and an external reference laboratory measuring E2 by LC-MS/MS. Our LC-MS/MS E2 assay shows acceptable accuracy, precision, functional sensitivity (LLoQ), and linearity for E2 quantification. Our LC-MS/MS E2 assay also showed good agreement with an external reference laboratory measuring E2 by LC-MS/MS. In addition, using CALIPER samples, we established robust age- and sex-specific pediatric E2 reference intervals to improve accuracy of test result interpretation and clinical decision making.

Pediatric reference intervals for Free Testosterone, 17-OH Progesterone, Androstenedione, and IGF-1 with chemiluminescence immunoassay

BackgroundThe aim of the study was to produce age and sex specific pediatric reference intervals (RIs) on a fully automated chemiluminescent immunoassay (CLIA) system. Material and methodA total of 1586 patients’ remnant sera were included in the study and free testosterone (FT), 17-OH progesterone (17OHP), androstenodione (A4) and insulin-like growth factor-1 (IGF-1) parameters were measured on MAGLUMI 2000 (Shenzhen New Industries Biomedical Engineering Co., Ltd. (Snibe), Shenzhen, China) CLIA analyser. After appropriate age and gender partitioning, specific intervals were calculated according to Clinical Laboratory Standart Institute’s (CLSI) C28-A3 protocol. ResultsAll analytes showed sex and age dependent concentrations requiring several subgroups with specific reference intervals. 17OHP and A4 were found high with birth, declined thereafter: 17OHP by the end of 12 months and A4 by 6 months. So this period was also partitioned for these two hormones. All showed gradual increases by the end of 18 years. 17OHP, A4 and IGF-1 of girls were higher than boys around puberty as the result of earlier sexual development and maturation. FT values of boys and girls didn’t differ from each other upto 10 years of age but boys had significantly higher values than girls afterwards. IGF-1 values gradually increase in both sexes upto the ages of 13, girls with significantly higher values than boys. In 13–18 years no significant gender difference was found. ConclusionsWe present method specific pediatric RIs, which are comparable with medical literature, necessary for interpretation of patient results.

Complex biological patterns of soluble cytokines and CD163 in childhood necessitating age-specific reference intervals for evidence-based clinical interpretation

BackgroundCytokine measurements to support clinical laboratory and research investigations have become increasingly common in pediatrics. However, there is a paucity of accurate pediatric reference intervals (RIs) essential to the interpretation of cytokine results. To address this gap, here, we establish age- and sex-specific pediatric reference values for clinically relevant inflammatory markers including CD163, and the cytokines IL-1β, IL-6, IL-10, IL-18, TNF-α, IFN-γ, and CXCL-9. MethodsHealthy children and adolescents (n = 311, 1–19 years) were recruited as part of the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) study. Multi-analyte measurements in plasma and analytical performance verification were conducted on the ProteinSimple® Ella™ automated immunoassay platform (Bio-Techne, MN, USA). Age- and sex-specific RIs were calculated based on Clinical and Laboratory Standards Institute guidelines. Additionally, 75th and 95th percentile cut-offs were determined. ResultsThree types of reference value distributions were observed: (a) consistent levels throughout age and sex: IL-6, and IFN-γ, (b) gradual decline in concentration with age: CD163, TNF-α, CXCL-9, and IL-10, (c) significantly higher concentrations during ages 4–14 years than earlier and later ages: IL-1β and IL-18. Reference values for CXCL-9, IL-10, and TNF-α under 8 years of age differed significantly from older children. CD163, IL-18 and IL-1β required three age partitions. CD163 demonstrated significant sex differences in ages 8–13 years. ConclusionThe circulating profile of cytokines in children is complex and can vary by age and sex. This necessitates careful interpretation of test results based on age and/or sex specific RIs facilitating more accurate clinical decision making.

Age- and Sex-Specific Pediatric Reference Intervals of Serum Electrolytes in Jilin Province of China Using the A Priori Approach.

ObjectivesThe purpose of this study was to establish age- and sex-specific pediatric reference intervals of serum potassium (K), sodium (Na), chlorine (Cl), calcium (Ca), magnesium (Mg), and phosphorus (P) using a direct sampling technique.MethodsIn accordance with the a priori approach, healthy individuals (n = 6,466, aged 1 month to <18 years) were enrolled from five regions in Jilin Province, China, and all analytes were performed in the center laboratory. Reference intervals were divided according to the regression tree and Harris and Boyd’s method, and then they were calculated by the nonparametric rank method. The dynamic changes of reference intervals were evaluated by the lambda-mu-sigma (LMS) method.ResultsReference intervals of serum Na and Ca were divided into three age-specific partitions. The concentrations of K, Cl, and Mg remained stable with age. However, only dramatic sex-specific changes of P were shown in those 11 to less than 13 years old and 13 to less than 15 years old, with an earlier peak time in females than in males. The correlation between Na and Cl was the strongest among all serum electrolytes (r = 0.31).ConclusionsSerum electrolyte reference intervals for children and adolescents were established by regression tree, z test, and the LMS method, which provide a more accurate interpretation for diagnosis and prognosis evaluation of clinical pediatric diseases.

CALIPER Hematology Reference Standards (II).

The objective of this study was to establish comprehensive age- and sex-specific reference intervals for hematologic parameters in the CALIPER cohort of healthy children and adolescents. A total of 536 healthy children and adolescents (birth to 21 years) were recruited with informed consent, and whole blood samples were analyzed for 27 hematologic parameters on the Beckman Coulter DxH 520 system. Age- and sex-specific pediatric reference standards were established. Reference values obtained on the DxH 520 were also compared with data obtained on a larger laboratory-based instrument (DxH 900). Most hematologic parameters showed significant age- and/or sex-specific changes during growth and development. Of the 27 hematologic parameters, all except four (mean corpuscular hemoglobin concentration, basophil percentage, low hemoglobin density, immature cell percentage) required age partitioning, and eight required sex partitioning. This study establishes a robust pediatric hematology reference database that will assist in more accurate test result interpretation. Our data clearly demonstrate significant variation in hematologic parameter concentrations in children and adolescents, necessitating the use of pediatric-specific reference standards.

Establishing pediatric reference intervals for 13 biochemical analytes derived from normal subjects in a pediatric endocrinology clinic in Korea

ObjectivesDefining pediatric reference intervals is one of the most difficult tasks for laboratory physicians. The continuously changing physiology of growing children makes their laboratory values moving targets. In addition, ethnic and behavioral differences might also cause variations. The aim of this study was to establish age- and sex-specific partitioned reference intervals for 13 serum biochemical analytes in Korean children. Design and methodsA total of 2474 patients, girls aged 2–14years and boys aged 2–16years, who underwent a short stature workup but were diagnosed as normal at the Pediatric Endocrinology Clinic of Severance Hospital (Seoul, Korea) between September 2010 and June 2012 were included in this study. The levels of serum calcium, inorganic phosphorus, blood urea nitrogen, creatinine, uric acid, glucose, total cholesterol, total protein, albumin, alkaline phosphatase, aspartic aminotransferase, alanine aminotransferase, and total bilirubin were measured using a Hitachi 7600 analyzer (Hitachi High-Technologies Corporation, Tokyo, Japan). Reference intervals were partitioned according to sex or age subgroups using the Harris and Boyd method. ResultsMost analytes except calcium and albumin required partitioning either by sex or age. Age-specific partitioned reference intervals for alkaline phosphatase, creatinine, and total bilirubin were established for both males and females after being partitioned by sex. Additional age-specific partitioning of aspartic aminotransferase in females and total protein and uric acid in males was also required. Inorganic phosphorus, total cholesterol, alanine aminotransferase, blood urea nitrogen, and glucose were partitioned only by sex. ConclusionsThis study provided updated age- and sex-specific pediatric reference intervals for 13 basic serum chemistry analytes from a sufficient number of healthy children by using a modern analytical chemistry platform.

Pediatric reference intervals for 28 chemistries and immunoassays on the Roche cobas® 6000 analyzer—A CALIPER pilot study

Objective The aim of this study was to determine age- and sex-specific pediatric reference intervals for 28 analytes on the Roche cobas ® 6000 analyzer. Design and methods The study was conducted at the Hospital for Sick Children in Toronto, Canada. Approximately 600 outpatient samples from a pediatric population deemed to be metabolically stable were subdivided into five age classes ranging from 0 to 20 years of age and further partitioned by gender. Reference intervals were established, after removal of samples significantly affected by hemolysis, icterus and lipemia and outlier exclusion, using the Robust statistical method to obtain the 2.5th and 97.5th percentiles. Results Age (birth to 20 years of age) and gender-appropriate pediatric reference intervals for 28 analytes are reported. Conclusions These reference intervals provide the basis for clinical interpretation of laboratory results using the Roche cobas ® 6000 analyzer or related instrumentation/methods, provided adequate reference interval verification studies are performed.

Pediatric reference intervals for aldosterone, 17α-hydroxyprogesterone, dehydroepiandrosterone, testosterone and 25-hydroxy vitamin D 3 using tandem mass spectrometry

Objectives To determine age and sex-specific pediatric reference intervals for aldosterone, 17α-hydroxyprogesterone, dehydroepiandrosterone, testosterone, and 25-hydroxy vitamin D 3. Background and design Reference intervals were determined for neonates and children 0–18 years of age. The study was conducted at both Children's National Medical Center and Georgetown University using outpatient blood samples obtained between January 1, 2004 and June 30, 2008. Methods Serum samples were analyzed using isotope dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) with deuterium-labeled internal standards at Children's National Medical Center and Georgetown University Medical Center Bioanalytical Core Laboratory. Results and conclusions This is the first study to provide pediatric reference intervals of steroid hormones for children from birth to 18 years of age using LC/MS/MS. Reference intervals were established for aldosterone, 17α-hydroxyprogesterone, dehydroepiandrosterone, testosterone, and 25-hydroxy vitamin D 3. All the analytes exhibited at least some age dependence. Sex differences between early and late childhood and adolescence were found for 17α-hydroxyprogesterone and testosterone. Seasonal differences were apparent for 25-hydroxy vitamin D 3.

Pediatric reference intervals for thyroid hormone levels from birth to adulthood: a retrospective study

BackgroundAge- and sex-specific reference intervals are an important prerequisite for interpreting thyroid hormone measurements in children. However, only few studies have reported age- and sex-specific pediatric reference values for TSHbasal (TSH), free T3 (fT3), and free T4 (fT4) so far. Reference intervals are known to be method- and population-dependent. The aim of our study was to establish reference intervals for serum TSH, fT3, and fT4 from birth to 18 years and to assess sex differences.Methods2,194 thyroid hormone tests obtained from a hospital-based pediatric population were included into our retrospective analysis. Individuals with diagnoses or medications likely to affect thyroid function were primarily excluded, as well as the diagnostic groups, if different from the purely healthy subgroup (n = 414). Age groups were ranging from 1 day to 1 month, 1 – 12 months, and 1 – 5, 6 – 10, 11 – 14, and 15 – 18 years, respectively. Levels of fT3, fT4 and TSH were measured on Advia® Centaur™ automated immunoassay system.ResultsThe final sample size for reference data creation was 1,209 for TSH, 1,395 for fT3, and 1,229 for fT4. Median and 2.5/10/25/75/90/97.5 percentiles were calculated for each age group. Males had greater mean fT3 concentrations than females (p < 0.001). No sex-differences were found for TSH and fT4 between age-matched serum samples. Median concentrations of fT3, fT4 and TSH were greatest during the first month of life, followed by a continuous decline with age.ConclusionOur results corroborate those of previous studies showing that thyroid hormone levels change markedly during childhood, and that adult reference intervals are not universally applicable to children. Moreover, differences of our reference intervals compared to previous studies were observed, likely caused by different antibody characteristics of various analytical methods, different populations or undefined geographic covariates, e.g. iodine and selenium status.

IMMULITE® 2000 age and sex-specific reference intervals for alpha fetoprotein, homocysteine, insulin, insulin-like growth factor-1, insulin-like growth factor binding protein-3, C-peptide, immunoglobulin E and intact parathyroid hormone

Objectives To determine age and sex-specific pediatric reference intervals for serum alpha fetoprotein, homocysteine, insulin, insulin-like growth factor-I, insulin-like growth factor binding protein-3, C-peptide, immunoglobulin E and parathyroid hormone. Design and methods The study was conducted at both Children's National Medical Center and Georgetown University, Washington D.C. Results for the above analytes were obtained from the Children's National Medical Center laboratory information system over the period of 1/5/2001–3/8/2007.Patient results using the IMMULITE 2000® were accessed and used to establish reference intervals for the analytes studied. All patient identifiers were removed except age and sex. Analysis of the data was performed at Georgetown University in the Bioanalytical Core Laboratory. The data was analyzed using the Hoffmann approach, and was computer adapted. The number of patient samples studied varied with each analyte and were: Alpha fetoprotein (557), homocysteine (924), insulin-like growth factor-1 (1352), insulin-like growth factor binding protein-3 (711), insulin (3239), C-peptide (267), immunoglobulin E (2691) and parathyroid hormone (513). Results and conclusions This study provides pediatric reference intervals for the eight analytes for children from birth to 18 years of age. All the analytes exhibited at least some age dependence. Sex differences between early and late childhood and adolescence were also frequently found.

Pediatric reference ranges on the Abbott IMx for FSH, LH, prolactin, TSH, T 4, T 3, freeT 4, freeT 3, T-uptake, IgE, and ferritin

The aim of the study was to produce age and sex specific pediatric reference intervals (RIs) on a fully automated chemiluminescent immunoassay (CLIA) system.A total of 1586 patients’ remnant sera were included in the study and free testosterone (FT), 17-OH progesterone (17OHP), androstenodione (A4) and insulin-like growth factor-1 (IGF-1) parameters were measured on MAGLUMI 2000 (Shenzhen New Industries Biomedical Engineering Co., Ltd. (Snibe), Shenzhen, China) CLIA analyser. After appropriate age and gender partitioning, specific intervals were calculated according to Clinical Laboratory Standart Institute’s (CLSI) C28-A3 protocol.All analytes showed sex and age dependent concentrations requiring several subgroups with specific reference intervals. 17OHP and A4 were found high with birth, declined thereafter: 17OHP by the end of 12 months and A4 by 6 months. So this period was also partitioned for these two hormones. All showed gradual increases by the end of 18 years. 17OHP, A4 and IGF-1 of girls were higher than boys around puberty as the result of earlier sexual development and maturation. FT values of boys and girls didn’t differ from each other upto 10 years of age but boys had significantly higher values than girls afterwards. IGF-1 values gradually increase in both sexes upto the ages of 13, girls with significantly higher values than boys. In 13–18 years no significant gender difference was found.We present method specific pediatric RIs, which are comparable with medical literature, necessary for interpretation of patient results.

Age- and sex-specific pediatric reference intervals for biochemistry analytes as measured with the Ektachem-700 analyzer.

Using the Ektachem-700 multilayer film analyzer, we defined age- and sex-specific reference intervals for 20 analytes in sera from a healthy population of neonates and children ages one to 19 years. Upper and lower normal reference intervals for each analyte were determined by nonparametric methods as the 0.975 and 0.025 fractiles, respectively. Newborns have lower concentrations of total protein and albumin, and higher concentrations of phosphate, bilirubin, and enzymes in serum than older children do. Concentrations of urea, glucose, calcium, phosphate, and bilirubin change rapidly postnatally. Outside the neonatal period, no significant age- or sex-related difference was found for plasma glucose, serum amylase, conjugated or unconjugated bilirubin, or lipase. There was no sex-related difference in reference intervals for albumin, total protein, calcium, phosphate, or urea. However, concentrations of uric acid and creatine kinase are much higher in postpubertal boys than in girls. Alkaline phosphatase values peak later in boys. Except for lactate dehydrogenase and gamma-glutamyltransferase, the reference intervals defined here do not differ strikingly from data derived with use of other analyzers. The age- and sex-related trends are independent of method. However, each laboratory should determine the degree to which these reference ranges can be directly applied to analyses performed with another analyzer.

Age- and sex-specific pediatric reference intervals and correlations for zinc, copper, selenium, iron, vitamins A and E, and related proteins.

Age- and sex-specific reference intervals based on the 0.025 and 0.975 fractiles of data derived from a healthy pediatric population are presented for zinc, copper, selenium, iron, ferritin, retinol, alpha-tocopherol, and related analytes in serum. Age was an important covariate for copper, selenium, retinol, and tocopherol, and ferritin in boys. Strong correlations were found between retinol and retinol-binding protein, prealbumin (transthyretin), alpha-tocopherol, and selenium. Tocopherol was highly correlated with both cholesterol and triglycerides. We found no relationship between serum zinc and either retinol or retinol-binding protein. Despite exclusion of children in whom anemia, microcytosis, or variant hemoglobins were found, the 0.025 fractile for iron in several age groups was even less than the concentration considered to indicate poor iron nutritional status.

Age- and sex-specific pediatric reference intervals: study design and methods illustrated by measurement of serum proteins with the Behring LN Nephelometer.

We analyzed blood from 450 healthy children and adolescents, ages one to 19 y, as well as term and preterm infants, to define age- and sex-specific reference intervals for numerous blood constituents. Reference intervals were derived by using nonparametric methods to determine the 0.025 and 0.975 fractiles. Ten serum proteins were measured with the Behring LN Nephelometer. Girls over 10 years of age had higher concentrations of ceruloplasmin and alpha 1-antitrypsin than other children had. There was no sex-related difference in reference intervals for the other proteins tested. Reference intervals are presented for immunoglobulins G, A, and M, complement fractions C3c and C4, ceruloplasmin, transferrin, alpha 1-antitrypsin, retinol-binding protein, and prealbumin (transthyretin).